eSIM API comparison: Firsty vs Twilio vs Telnyx for builders

This comparison focuses on what matters most to developers adding eSIM data to a consumer or business app: provisioning flow, network switching, pricing model and onboarding. It is based on each provider's public pages, checked on 27 October 2026. Other factors may matter for your use case.

Why this comparison exists

If you're adding an eSIM API to a travel app, a phone-number service, a device fleet or a banking app with data abroad, three names often come up: Firsty, Twilio Super SIM and Telnyx.

One thing changed recently. Twilio's IoT business was acquired by KORE, and Twilio Super SIM is now sold as KORE Super SIM (Twilio, checked 27 October 2026). We use that name below.

• Firsty: eSIM for travel, business and white-label brands, with real-time network switching, phone numbers and a free sandbox

• KORE Super SIM (formerly Twilio Super SIM): IoT SIM and eSIM for connected devices

• Telnyx IoT SIM and eSIM: connectivity on a carrier platform that also sells voice and messaging

We compare the flow from "user clicks buy" to "eSIM on the device", how each provider switches networks, how pricing is structured and what onboarding looks like.

TL;DR

All three providers are multi-network. The differences are in how you provision, who controls switching and how pricing is structured. Competitor details are from their own pages, checked 27 October 2026 (sources in each section).

1. Network switching: who controls it

All three providers give access to more than one network per country. The useful question is how switching works and how much of it you control.

• Firsty switches automatically to the strongest available network in real time. It monitors signal quality and switches before a connection drops. You can set network priorities and switching rules through the API and partner dashboard, and end users can override manually (Firsty).

• KORE Super SIM lists available and backup networks per country, for example four in Italy and three in Switzerland. The networks a device may use are set per Fleet through a Network Access Profile (KORE docs, checked 27 October 2026).

• Telnyx SIMs carry several IMSIs. An on-SIM applet picks the best one per location, with automatic failover when a network drops (Telnyx docs, Telnyx, checked 27 October 2026).

For travel and consumer apps, ask how fast switching happens on a moving device and whether your support team can change network rules without a code change. For static IoT devices, a fixed set of allowed networks per fleet may be all you need.

2. Provisioning API: SIM first, plan later

How you go from "user clicks buy" to "activation code on screen" shapes your checkout, top-ups and trials.

Firsty (two steps):

POST /v1/esims         → returns esimReference (instant)
POST /v1/esims/{ref}/plans  → attach a data plan when the user is ready

You can create the eSIM up front, so the activation code is ready at checkout, and attach plans later. This fits marketplaces, gift flows, top-ups and trial-to-paid conversions. See the quickstart.

KORE Super SIM: a SIM takes its capabilities from the Fleet it belongs to. You create a Fleet, add the SIM and then activate it. The Fleet sets the allowed networks and the data limit (KORE docs, checked 27 October 2026).

Telnyx: you buy eSIMs by API and can place them in a SIM card group. Data limits and network preferences are set on the group (Telnyx API reference, Telnyx docs, checked 27 October 2026).

The difference: with KORE and Telnyx, settings sit on a group of SIMs, which suits fleets of identical devices. With Firsty, each eSIM gets its own package, which suits products where every user buys a different plan.

Deeper dive: Why two-step eSIM provisioning beats single-call APIs

3. Pricing model: global rate vs per network or zone

• Firsty offers global plans at a single global rate, or country plans that cost less per GB. API pricing is based on usage and volume (Firsty API, Firsty docs).

• KORE Super SIM prices per SIM and per network. Each network may have a different price per MB, and an active SIM costs $2.00 a month (KORE, KORE docs, checked 27 October 2026).

• Telnyx prices data by zone and volume tier. In the US (Zone 1), data runs from $0.078 per MB for the first 100 MB to $0.0125 per MB above 5 GB. On top of that come $2 per SIM per month, and $1 per SIM card or $0.70 per eSIM (Telnyx pricing, checked 27 October 2026).

If you sell travel bundles ("Europe 5 GB / 30 days"), one global rate makes your end-user price easier to set. If you sell per-country IoT plans, per-network or per-zone pricing works, but plan for reconciliation work.

4. Onboarding: getting to a first eSIM

Typical onboarding steps, based on each provider's public documentation (checked 27 October 2026). We did not time these.

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5. Coverage and networks

All three publish coverage figures. As stated on their own pages:

• Firsty: 176 countries, with real-time switching to the strongest available network (Firsty).

• KORE Super SIM: over 400 networks in 188 countries, listed per country (KORE docs, checked 27 October 2026).

• Telnyx: 650+ networks in 180+ countries (Telnyx, checked 27 October 2026).

Whatever you choose, ask each vendor for its network list in your top countries and how switching behaves there.

6. Best fits

• Travel apps and consumer eSIM: Firsty. Real-time switching, two-step provisioning and global plans fit a consumer checkout.

• MVNO and white-label brands: Firsty. Every product can be white-labelled, from interface to checkout (Firsty API).

• Fintech with data abroad: Firsty. See the Belfius case study.

• When another provider may fit better: if you run a fleet of identical IoT devices and want to manage them in groups, KORE Super SIM or Telnyx are built around that model. If voice is your main product, Telnyx sells voice and messaging on the same platform.

FAQ

Is Twilio Super SIM still a Twilio product? No. Twilio's IoT business was acquired by KORE, and Super SIM is now KORE Super SIM (Twilio, checked 27 October 2026). Twilio's messaging and voice APIs are separate.

Can I switch providers later? An eSIM profile is tied to the provider that issued it. You can sell new eSIMs through a new provider in parallel, but you can't move active profiles between providers without installing a new profile on the user's device.

Does Firsty have a free tier? Yes. The sandbox is free, with no card or sales call. Test activation codes are mock data, so you can't install them on a phone. You pay only for production use.

What about Soracom, emnify and 1NCE? We didn't compare them in this guide. They're mainly used for IoT, so check their own pages if that's your use case.

Next steps

• Builders evaluating providers: Buying eSIMs in bulk: an honest checklist

• Builders comparing Firsty and Twilio specifically: Firsty vs Twilio: choosing a connectivity API

• Ready to integrate: Provision your first eSIM via API in 30 minutes

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